Films or sheets of polymeric barrier materials are formed into a finished package or "film package" such as a pouch by various techniques. For instance, by forming heat or adhesive seals about the periphery of the shape to be formed into a pouch. For example, if a square pouch is desired, a rectangular film twice the desired length of the pouch is folded, the two parallel sides of the periphery (perpendicular to the fold) heat or adhesive sealed, or, the two parallel sides and the fold are heat or adhesive sealed, the food or other material to be packaged inserted therein, and then the remaining open side of the periphery is heat or adhesive sealed. Another method for making a pouch is by sealing on three sides face-to-face films, filling the thus formed open pouch with food or whatever material is to be packaged therein, and then sealing the fourth side. For background on pouches and their production, reference is made to U.S. Pat. Nos. 4,190,477, 4,311,742, 4,360,550, and 4,424,256, each of which being hereby incorporated herein by reference.
The problem encountered by the end user of the food or material within the pouch is how to open the pouch. The pouches are usually formed from tough or strong polymeric barrier materials so the pouches do not open easily. One method for opening such pouches is to manually rip at the pouch which usually results in its contents spilling all about. Another method is simply cutting open the pouch with a scissor, knife or other sharp object. It is desirable to be able to neatly open a pouch without the need to use a cutting instrument. Furthermore, the problem of how to open a pouch is really two fold: The first problem is how to initiate the opening. The second problem is providing control of the opening across the entire pouch.
To meet this desire of being able to open a pouch without a cutting instrument, some have proposed packages having an opening notch such as V- or I-shaped notch or notches, or a tearing zone, see e.g., U.S. Pat. Nos. 4,934,245, 3,404,988. U.S. Pat. No. 3,693,785 relates to a wrapping material containing regenerated cellulose which has a portion thereof which is more frangible than the remainder thereof. Likewise, U.S. Pat. No. 3,986,640 deals with a flexible package having a cut pattern, which, when bent along the cut pattern, causes the package to open and the flowable contents therein to dispense. U.S. Pat. No. 4,217,327 relates to forming a score line along a predetermined line in the surface of a plastic film to form a tear line. And, U.S. Pat. No. 4,236,652 relates to a package having a cut score area to rupture open the package upon bending.
These previous proposals have not overcome the problem. Notches, cut patterns or tear lines can produce an opening which is easily propagated without any control. Further, notches, cut patterns or tear lines produce areas of weakness in the package, which, when stressed accidentally, e.g., during handling or shipping, can become an unintended opening which is easily propagated. That is, these proposals have not adequately resolved the problem of initiating an opening only when desired and of controlling the opening across the entire package.
Furthermore, these proposals have presented manufacturing problems. For instance, the problem of properly locating the notch, cut pattern or tear line in a position where the consumer desires to open the package. If not properly positioned, the resulting package can be worse than if no such notch, cut pattern or tear line had been provided: The consumer must still resort to a sharp object to open the package, but it is weakened at some point (due to the mispositioned notch, cut pattern, or tear line). In addition, opening features such as those on cigarette packs require a separate opening tape which means that it is more costly to manufacture the package because it requires a separate material (the tape) and a complicated process.
Roughening an area of the package is another type of proposal to open a package without the need for a cutting instruments. U.S. Pat. No. 3,313,642, incorporated herein by reference, relates to a process of modifying the surface properties of polyolefin film.
U.S. Pat. No. 4,778,058 provides a pouch from a film of two plastic layers. A discreet area of the first layer, corresponding to a folded portion of the resultant pouch, is surface roughened prior to lamination to the second layer. The irregularities from roughening are filled with the plastic material of the second plastic layer. The film of the two layered film is heat-sealed into a pouch. The surface roughening is at a position on the first layer of the film other than the portion thereof to be heat sealed. While U.S. Pat. No. 4,778,058 may provide for tear initiation, it still fails to provide for control of the tear as is desired by the end user.
U.S. Pat. No. 4,543,279 relates to a film product, such as a sealed bag, wound film or adhesive tape, having a plurality of random scratches or cuts formed along the edges and oriented toward the other side of the film. In a bag of U.S. Pat. No. 4,543,279, the scratches are formed on the longitudinal edge portion of the bag, outside of the seals thereof, or on the longitudinal edge portion outside of the seal and on a central line inside the seal. There is no teaching or suggestion to roughen areas of films where the seals of a resultant pouch are to be located. Further, while placing scratches on a central line inside the seal may provide for tear initiation, the placement of the scratches outside of the seals may not adequately provide for tear initiation as the user must still rip through the seals. And, no provision is made for tear control.
U.S. Pat. No. 3,608,815 relates to an opening aid for packages made from at least one oriented material. The opening aid consists of minutely expanding the oriented material at a plurality of points within an area pattern which will be a fold (and not a seal) of the package. U.S. Pat. No. 3,608,815 simply provides tear initiation like the previously discussed notch or cut techniques. However, U.S. Pat. No. 3,608,815 chalks up tear control to the nature of the materials of the package, stating that oriented materials "tear in an essentially straight line" while cellophane will tear without directional control. Thus, U.S. Pat. No. 3,608,815 does not adequately provide tear control.
Japanese Utility Model Publication No. 54-22484, published Aug. 6, 1979 (Application No. 50,68727 dated May 23, 1975; Early Disclosure No. 51-150915, dated Dec. 2, 1976), relates to a bag having seals with tear-initiating lines. The tear initiating lines consist of ordered, successively smaller pinholes or notches extending from the outer edge of the seal and terminating at the center of the seal so that the inner half of the seal is the same as an ordinary seal. It is stated in this publication that the holes or notches are not to extend all the way into the enclosed part of the bag, i.e., across the entire width of the seal, because to do so will impair the strength and the airtightness of the seal. Further, this publication poses manufacturing problems which it leaves unaddressed. To effect the tear-initiating line, the films of the bag must be selectively cut or notched: The cuts or notches are organized along lines and are of varying size and extend only through one-half of the seal. Thus, this publication calls for a very complicated manufacturing process.
Japanese Patent Publication No. 51-48775, published Dec. 22, 1976 (Application No. 49-49804 dated May 7, 1974; Early Disclosure No. 51-16346, dated Feb. 9, 1976), deals with placing minute scars, embossment or scratches along the center line of a laminate plastic film which is then slit lengthwise along the center line to make two adhesive tapes. The problems of tear initiation and tear control in the opening of packages are not addressed in this publication.
Thus, heretofore, it has not been taught or suggested to roughen portions of an outer or inner surface of a film along an edge or portion thereof which is at least the full width of at least one seal when the film is made into a pouch so that the pouch has an easy tear-open feature edge (tear initiation) inward at the localized area of the seal (tear control).
Heretofore, a continuous laminate film which is extruded and surface roughened on the outer or inner surface at an isolated area which is to be at least the full width of at least one of the seals when the film is made into a pouch so that the pouch has an easy tear-open feature edge inward at the localized area of the seal has not been taught or suggested.
Further, heretofore, a continuous laminate film of (outer surface) polyester/vinylidene chloride copolymer/ink/primer/LDPE/EVA/Surlyn (Du Pont)/Surlyn (inside surface) which is extruded and roughened on the outer or inner surface of the polyester layer at an isolated area which is to be at least the full width of at least one of the seals when the film is made into a pouch so that the pouch has an easy tear-open feature edge inward at the localized area of the seal, has not been taught or suggested.
It is thus an object of this invention to provide a pouch which is not complex to manufacture (and thus less costly than prior pouches) and which has tear initiation and tear control features by being formed from a continuous laminate film which is extrusion laminated and roughened on the outer or inner surface at an isolated area which is to be at least a full width of at least one of the seals of the resultant pouch.